An ab initio calculation of the electric-field gradient(EFG)at the site of a phosphorous impurity substituting an Al atom in α-Al_(3)O_(2) is carried out using the WIEN2k code with the full-potential linearized augme...An ab initio calculation of the electric-field gradient(EFG)at the site of a phosphorous impurity substituting an Al atom in α-Al_(3)O_(2) is carried out using the WIEN2k code with the full-potential linearized augmented plane wave plus local orbital method(LAPW+lo)in the frame of density functional theory.The atomic lattice relaxations caused by the implanted impurities were calculated for two different charged states to well describe the electronic structure of the doped system.The EFG at the site of the phosphorous impurity in the charged supercell calculated with the exchange-correlation potential of the Wu-Cohen generalized gradient approximation(WC-GGA)is 0.573×10^(21) V/m^(2).Then,the nuclear quadrupole moment of the I=3 state in ^(28)P is deduced to be 137 mb from the quadrupole interaction frequency of 190 kHz measured recently by theβ-NQR method.展开更多
The void evolution inα-Al2O3 irradiated by En≥1 MeV neutrons of 3×10^(20)cm^(-2) and post-annealed from 100°C to 1050°C has been studied by a positron annihilation lifetime technique.The void nucleati...The void evolution inα-Al2O3 irradiated by En≥1 MeV neutrons of 3×10^(20)cm^(-2) and post-annealed from 100°C to 1050°C has been studied by a positron annihilation lifetime technique.The void nucleation starts at 500°C.In the annealing temperature region from 550℃ to 750℃,the radius of created voids keeps constant at a value of about 0.29 nm and the number of voids increases with increasing temperature.Afterwards,the radius of voids increases rapidly with the increasing annealing temperature and reaches 1.21nm at 1050℃.展开更多
The g-factors of the rotational states along the positive parity yrast band in even-even nuclei ^(84)Zr were measured up to a spin I=16^(+)by a transient magnetic field-ion implanted perturbed angular distribution met...The g-factors of the rotational states along the positive parity yrast band in even-even nuclei ^(84)Zr were measured up to a spin I=16^(+)by a transient magnetic field-ion implanted perturbed angular distribution method and calculated by a cranking shell model.A peak structure of the g-factors has been observed for the first time.The measured g-factors confirm the mixed configuration of proton and neutron alignments.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos 10975189 and 91126002.
文摘An ab initio calculation of the electric-field gradient(EFG)at the site of a phosphorous impurity substituting an Al atom in α-Al_(3)O_(2) is carried out using the WIEN2k code with the full-potential linearized augmented plane wave plus local orbital method(LAPW+lo)in the frame of density functional theory.The atomic lattice relaxations caused by the implanted impurities were calculated for two different charged states to well describe the electronic structure of the doped system.The EFG at the site of the phosphorous impurity in the charged supercell calculated with the exchange-correlation potential of the Wu-Cohen generalized gradient approximation(WC-GGA)is 0.573×10^(21) V/m^(2).Then,the nuclear quadrupole moment of the I=3 state in ^(28)P is deduced to be 137 mb from the quadrupole interaction frequency of 190 kHz measured recently by theβ-NQR method.
基金Supported in par t by the National Natural Science Foundation of China under Grant No.19835050the Nuclear Indus try Science Foundation of China under Grant No.H7196BO116the Contract of 97J11.2.8HZ010.
文摘The void evolution inα-Al2O3 irradiated by En≥1 MeV neutrons of 3×10^(20)cm^(-2) and post-annealed from 100°C to 1050°C has been studied by a positron annihilation lifetime technique.The void nucleation starts at 500°C.In the annealing temperature region from 550℃ to 750℃,the radius of created voids keeps constant at a value of about 0.29 nm and the number of voids increases with increasing temperature.Afterwards,the radius of voids increases rapidly with the increasing annealing temperature and reaches 1.21nm at 1050℃.
基金Supported by the National Natural Science Foundation of China under Grant No.19775070.
文摘The g-factors of the rotational states along the positive parity yrast band in even-even nuclei ^(84)Zr were measured up to a spin I=16^(+)by a transient magnetic field-ion implanted perturbed angular distribution method and calculated by a cranking shell model.A peak structure of the g-factors has been observed for the first time.The measured g-factors confirm the mixed configuration of proton and neutron alignments.
